Does class D have the Heft of SS

[AE1]

AE-1, you have made some bad assumptions in your simplistic analysis which leads to your incorrect analysis.

Comment: "Simplicity" is the solution to all complex problems

[QUOTE="First of all, the amount of energy storage is proportional to the square of the voltage for a given capacitance. So, there is more energy storage in 500uF at 500V than 10,000uf at 50V (using the tube amp versus Peavey example).[/QUOTE]

Comment: That is not in dispute but I was referring to any given amplifier being improved by adding capitance to the power supply. So if the amp has 5,000 uF ex factory, adding another 5,000 uF at the same voltage will improve audio performance.

There is no standard size for capacitance v rail voltage v power output - otherwise all amps would be the same.

Modern amplifiers use rail voltages of around 100 VDC with fewer power transistors for lower cost whereas older amps run at maybe 50-60 volts. Obviously an amp running at 100 VDC requires less capacitance than one at 50 V because for the same rated power output the DC current is less - but the attenuating effect of AC series impedance with the speaker remains the same

It is the case that as capacitors have become physically smaller over the past 50 years, designers have increased the capacitance values used in power supplies.

Capacitors also come with a range of current ratings - eg "high ripple current" - so it does not follow that all capacitors of any given capacitance rating will perform the same.

Obviously such modifications need to be installed by a qualified technician and would void any manufacturer's warranty.

The other way to go is to simply use a larger amplifier - eg 500 watts instead of 100.

[QUOTE="Power amp energy storage (and transformer performance) go hand in hand and needs to be large enough to provide adequate filtering for the maximum current draw of the amp. Larger amps need larger power supplies.[/QUOTE]

Comment: I do agree there is a practical limit for capacitor size for any given wattage amp for reasons including safety, reliability, physical space and cost, but no matter what electronic wizardry is included in the power supply the fact is we get nothing for nothing where power is concerned - ie power out = mains power in minus rectification losses

A bass amp requires a more powerful power supply and better LF frequency response than a guitar amp or PA of similar wattage, because the low range audio frequencies require more power out to drive the speakers at an equivalent SPL to the mid range frequencies produced by other instruments

[QUOTE="Secondly, increasing the size of the fuse can't just happen because you increase the amount of capacitance. [/QUOTE]

Comment: Fuse size is related to surge current and must be proportional to requirements. The purpose of a fuse is to protect the source and not the load. A fuse could be installed between the rectifier and transformer to protect the transformer but always a fuse is installed to protect the mains from the amplifier.

[QUOTE="If you are designing a safe, agency certified product, the stresses on the components/wiring will be analyzed, and testing will be done to insure that the larger fuse value will open properly to clear the fault. If it doesn't (a likely issue) then additional changes will be necessary in order to insure safety. It is likely that the transformer will be operating in saturation during power-up under such high capacitance conditions.[/QUOTE]

Comment: The above analysis suggests - for example - a 2000 or 5000 watt amplifier is not safe because it draws a lot of current from the mains and will have a high total numeric value of filter capacitors and higher current fuses

Yet there are many successful high powered bass amplifiers on the market - e.g. the Bugera "Nuke" 3600 Watt bass amp. (That's peak watts by the way). It incorporates a circuit breaker instead of a simple mains switch.

[QUOTE="Under an amplifier fault condition, all that power supply energy must be dissipated somewhere. Unless specific design elements are included, this energy will often cause catastrophic damage to the amplifier components and PCB, resulting in an unrepairable amp, and possibly unacceptable risk of fire (will be looked at during a safety agency evaluation.[/QUOTE]

Comment: Higher powered amps often incorporate magnetic circuit breakers, which operate faster than fuses. It is always a question of costs v benefits - or risk

All designs are ultimately compromises so it is in the hands of the designer to determine solutions for every parameter.

[QUOTE="May sound like a good idea until the bigger picture is considered. Then the good idea doesn't seem quite as good as it once did.[/QUOTE]

Response:

I am puzzled

The underlying issue is the question of how the audio power output is measured. RMS ratings have always been continuous but peak watts can be of a very short time duration - the time interval itself used for the rating is rarely specified or revealed.

RMS watts equals the equivalent numeric DC watts - eg 100 watts rms = 100 watts DC - but peak power or peak music power or any other peak rated system increases the numeric value without a corresponding increase in DC equivalent.

Since mains power is measured in rms watts it follows that rectified mains watts = the maximum DC watts available to the amplifier

Power supplies can be conservatively rated, "average" or stress rated - depends upon the design

We see many different approaches to power supply design and so long as they work well there is no problem

But that is not the point of adding capacitance over and above the minimum required for adequate "normal" operation.

Many commercial amplifiers incorporate power transformers rated at 70% of rated rms amplifier power, on the basis that the amplifier power output on speech will average at 70%, permitting a smaller, lighter and cheaper power supply for the typical user on most occasions.

Subject to design analysis, such amplifiers may be improved by adding more filter caps.

Note: My Peavey Tour 700 has a 1000 watt power transformer so is conservatively designed - but I have still added more filter capacitance to improve bass response.

The addition of surplus capacitance provides a store of energy which is immediately available to the amplifier power stage whilst decreasing the series capacitance to the speaker load - i.e. adds "headroom" to the available power.

One way of addressing the low frequency response issue in two channel (stereo) PA amps is to use an amp having a common power supply to both channels. This way the series capacitance will usually have a higher value than that for separate power supplies.

This feature improves the "sound" of the amp - but of itself cannot cancel out other overall system shortcomings like poor speakers. It is just another enhancement option.

In the end it is the bass player who decides which is best for his or her purpose.

None of the above is helpful to non-technical bass players, who must rely upon manufacturers' claims and specifications.

My commentary is for those who understand.

The original post was about mains power consumption so again it is simply a case of audio power out = power in minus losses in the power supply and output stage

If readers do not agree please respond with your own opinions - is just my point of view based upon my own experience

 

[JimiLL]

The crest pro lite I had didn’t hit as hard as my carvin dcm 1500. In an a/b test

 

[Isotonic]

I remember my first experience with class-D. I was shopping for a new head. It had been a while. At the time, I had no experience of Class D Bass amps and no opinion. I auditioned about 5 different models, Orange, Genz-Benz, TC, and Aguilar. They all sounded different but something was missing. They were all plenty loud. Finally I checked out a used Genz-Benz 1200. Even at modest volume the difference was clear. The traditional Class AB circuit on the GB1200 was had a fast transient in the low frequencies that I found much more appealing.

Part of the issue, I think is how you play. In my case, I play the bass to guide and control the Rhythm section, and I am also melodic at times. But for me, fast transient response on the low frequencies helps me communicate with the drummer more clearly. I play a tight and rhythmic line that benefits from a fast attack at the lowest mids (80 to 200hz) and I need my amp to respond precisely to it. So to me, the responsiveness of AB amps is essential.

Too bad for me because I well into my 50's and my back could use a break.

However, there are some very nice sounding Class D amps out there. There are lots of players that I admire, who do not play the bass like a drum as I do. They simply have a different style and different needs. So for those players, there may be no appreciable difference.

 

[DavesnothereCA]

....when comparing two amps with the same power rating, one class-D and one traditional....

~
How does a person even KNOW when two amps have the same power rating these days ?!

The below-linked thread touches upon why I asked this, and it is not necessarily an issue of whether or not an amp is a Class 'D'.

Are RMS Watts a Thing of the Past ?
~

 

[JimiLL]

The progression of the class d argument:

It sounds identical.
Ok, not identical but it’s not enough difference to tell them apart.
Ok, you can tell them apart, but I and 99% of the audience can’t tell the difference.
Ok I can tell the difference, but it’s not enough for you to be worried about.

Usually it takes a new generation of amps to come out before people start being honest about the shortcomings of what they had

 

[Loring]

The progression of the class d argument:

It sounds identical.
Ok, not identical but it’s not enough difference to tell them apart.
Ok, you can tell them apart, but I and 99% of the audience can’t tell the difference.
Ok I can tell the difference, but it’s not enough for you to be worried about.

Usually it takes a new generation of amps to come out before people start being honest about the shortcomings of what they had

It doesn't have to sound identical.. two different branded tube amps won't sound identical either.
If it sounds good and has the authority in tone you like - that's all you need. I traded in an svt in the eighties because I liked the sound of an all SS mosfet trace elliot. Yeah they sounded different. That's was the point. If they sounded the same...
Now I have a wonderful class D Genzler Magellan 800. It has all the authority of my previous amps and weighs next to nothing. Sound is incredible especially paired with a new neo cab ( another genzler product a BA12-3)
This is the best sounding and lightest rig I've ever owned - sorry to all the TE and SVT fanboys...

 

[son_of_mogh]

Some guys on the Quilter Bass Block 800 thread have testified that IT has the most heft and 3D punch of any class D amp they know. That piqued my interest, for sure.

 

[Loring]

It may.. .
I haven't tried it. I have tried the mesa subway and the genzler. Both outstanding amps.

 

[JimiLL]

It doesn't have to sound identical.. two different branded tube amps won't sound identical either.
If it sounds good and has the authority in tone you like - that's all you need. I traded in an svt in the eighties because I liked the sound of an all SS mosfet trace elliot. Yeah they sounded different. That's was the point. If they sounded the same...
Now I have a wonderful class D Genzler Magellan 800. It has all the authority of my previous amps and weighs next to nothing. Sound is incredible especially paired with a new neo cab ( another genzler product a BA12-3)
This is the best sounding and lightest rig I've ever owned - sorry to all the TE and SVT fanboys...

I think the context of my response has escaped you

 

[BassmanPaul]

To answer the question in the title the answer is yes and Class D IS solid state though it doesn’t have to be.

 

[JimmyM]

The progression of the class d argument:

It sounds identical.
Ok, not identical but it’s not enough difference to tell them apart.
Ok, you can tell them apart, but I and 99% of the audience can’t tell the difference.
Ok I can tell the difference, but it’s not enough for you to be worried about.

Usually it takes a new generation of amps to come out before people start being honest about the shortcomings of what they had

That's exactly how it played out when SS started getting a foothold in the industry 40-50 years ago.

 

[JimmyM]

This is the best sounding and lightest rig I've ever owned - sorry to all the TE and SVT fanboys...

Why would we care? Ampeg and Trace make micros, too.

 

[JimiLL]

It’s funny because so many years ago when micros were first coming out you had a demographic of people that swore up and down that these new amps had no drawback, sounded just as good at any volume as lead sleds did, and would stop just short of questioning your intelligence if your opinion differed.

Now that there’s a new generation of micros, these same people are saying they can’t believe how much these new amps have improved upon the prior models in sound and feel

I think every adult could benefit from taking an entry level psychology course.

 

[JimmyM]

It’s funny because so many years ago when micros were first coming out you had a demographic of people that swore up and down that these new amps had no drawback, sounded just as good at any volume as lead sleds did, and would stop just short of questioning your intelligence if your opinion differed.

Now that there’s a new generation of micros, these same people are saying they can’t believe how much these new amps have improved upon the prior models in sound and feel

I think every adult could benefit from taking an entry level psychology course.

LOL!

Not gonna front...I have always been highly impressed by micros since the first wave of Markbass and Genz Benz micros hit in the mid-to-late-2000's. I actually liked them better than my SS amp at the time, which was an SWR SM-500, and I almost liked them better than tube amps. But then I got my tube amps restored and fixed properly and there was just no comparison. And I still feel that way 10 years later, except I now see why some folks still prefer their lead sled SS amps. But while I do have plenty of micros and feel that they've been improved upon since those days, I hear everything that those who don't like them hear in them, and they are not wrong. They are perfectly usable and many do sound excellent, and like I've pointed out before, their preamps go direct to the board as well as any preamps of similar quality. But to tell us there's no difference is rather insulting and unnecessary. People will still buy them regardless, and the industry pros who make them should stop with trying to convince us that we're wrong about what we hear. We're not.

 

[GreyBeard]

After 18 pages and we still haven't come up with a good definition of heft.

 

[Loring]

Why would we care? Ampeg and Trace make micros, too.

Tbh I wish I still had the svt. It did have s certain sound and gut punch I liked but mostly cause it was the first amp I toured with.

 

[Bob Lee (QSC)]

RMS ratings have always been continuous but peak watts can be of a very short time duration

So-called "RMS" watts are not necessarily continuous; they can also be short-term. An RMS voltage can be measured accurately in even just a single cycle.

 

[mikewalker]

...Then he realized that he had used one preamp the entire time. He changed that and practically everything he touched sounded great... which lead to him kicking himself over all of the gear he had dumped in his search, often at a substantial loss.

I would hazard a guess that as far as commercial bass amps go, 90% of "the sound quality" is coming directly from the preamp side.

 

[JimmyM]

I would hazard a guess that as far as commercial bass amps go, 90% of "the sound quality" is coming directly from the preamp side.

It's that 10% that's the real sticking point, then

 

[agedhorse]

Response:

I am puzzled

The underlying issue is the question of how the audio power output is measured. RMS ratings have always been continuous but peak watts can be of a very short time duration - the time interval itself used for the rating is rarely specified or revealed.

Yes, it is obvious that you are puzzled. Maybe I can help "unpuzzle" you, but you need to be willing to open your mind a bit and accept that what you have been posting is not correct.

RMS based ratings have nothing to do with continuous, they can be for whatever duration as long as it's for a complete cycle. Peak based ratings can also be for whatever duration is deemed appropriate.

RMS and PEAK only have to do with amplitude, the other important variable is time (which is where continuous or whatever duty cycle is deemed appropriate for the product comes from)

RMS watts equals the equivalent numeric DC watts - eg 100 watts rms = 100 watts DC - but peak power or peak music power or any other peak rated system increases the numeric value without a corresponding increase in DC equivalent.

Before getting too deep into the DC equivalent, you might want to think about how the load (speaker) would respond to the DC equivalent over time. In fact, speakers too are rated based on both amplitude and time, just like amplifiers.

Since mains power is measured in rms watts it follows that rectified mains watts = the maximum DC watts available to the amplifier

Based on 100% duty cycle, which of course no music is. The real question you should be exploring is how the interaction between duty cycle of an output waveform and the power supply is handled.

Power supplies can be conservatively rated, "average" or stress rated - depends upon the design

We see many different approaches to power supply design and so long as they work well there is no problem

Right, so why is there a problem?

But that is not the point of adding capacitance over and above the minimum required for adequate "normal" operation.

Who said anything about "minimum required"?

Many commercial amplifiers incorporate power transformers rated at 70% of rated rms amplifier power, on the basis that the amplifier power output on speech will average at 70%, permitting a smaller, lighter and cheaper power supply for the typical user on most occasions.

Here's where you start going very wrong in your assumptions. The average power of speech is almost always less than 12.5% (duty cycle), even most music is less that 12.5%. Your 70% number is simply wrong and misleading.

Subject to design analysis, such amplifiers may be improved by adding more filter caps.

Maybe, and maybe not. No way to say without doing the calculations... unless you are into guessing.

Note: My Peavey Tour 700 has a 1000 watt power transformer so is conservatively designed - but I have still added more filter capacitance to improve bass response.

Sometimes larger transformers are used simply because it's less expensive to use an already agency approved (costly process) transformer in higher quantities than using smaller quantities of a slightly less expensive transformer once all the factors are considered.

The addition of surplus capacitance provides a store of energy which is immediately available to the amplifier power stage whilst decreasing the series capacitance to the speaker load - i.e. adds "headroom" to the available power.

One way of addressing the low frequency response issue in two channel (stereo) PA amps is to use an amp having a common power supply to both channels. This way the series capacitance will usually have a higher value than that for separate power supplies.

This only applies IF the peak amplitude of the output is within the (Vunloaded - Vsag - Vripple), if it is not, then the size of the filter cap doesn't even come into play.

This feature improves the "sound" of the amp - but of itself cannot cancel out other overall system shortcomings like poor speakers. It is just another enhancement option.

In the end it is the bass player who decides which is best for his or her purpose.

None of the above is helpful to non-technical bass players, who must rely upon manufacturers' claims and specifications.

My commentary is for those who understand.

Actually, it's not helpful even to those who understand, because you have completely ignored duty cycle whichis THE elephant in the room regarding average versus peak power supply consumption.

The original post was about mains power consumption so again it is simply a case of audio power out = power in minus losses in the power supply and output stage

Without duty cycle, your argument has no real world basis.

[/QUOTE]

I remember my first experience with class-D. I was shopping for a new head. It had been a while. At the time, I had no experience of Class D Bass amps and no opinion. I auditioned about 5 different models, Orange, Genz-Benz, TC, and Aguilar. They all sounded different but something was missing. They were all plenty loud. Finally I checked out a used Genz-Benz 1200. Even at modest volume the difference was clear. The traditional Class AB circuit on the GB1200 was had a fast transient in the low frequencies that I found much more appealing.

Part of the issue, I think is how you play. In my case, I play the bass to guide and control the Rhythm section, and I am also melodic at times. But for me, fast transient response on the low frequencies helps me communicate with the drummer more clearly. I play a tight and rhythmic line that benefits from a fast attack at the lowest mids (80 to 200hz) and I need my amp to respond precisely to it. So to me, the responsiveness of AB amps is essential.

Well, since I designed your 1200, let me suggest a few things that might have gone unnoticed. The preamp in the 1200 has a few design features that are responsible for a good part of what you are hearing. If you were to take the preamp out, into the power amp in of anything class D that I have designed, you will find that the difference is quite a bit less that using the preamps of the class D amps that you tried.

The products that I designed using class D power amps by intention have different preamps that specifically appeal to different markets. For example, the Shuttlemax 9.2 is probably the closest to your GBE-1200, but the Shuttle was intended from the start to focus on the emerging compact amp/speaker market (and was quite successful), whereas the Streamliner series was totally different and appealed more to those who preferred more of the tube amp tone/feel. Some players loved the Shuttles but hated the Streamliners and some loved the Streamliners and hated the Shuttles. Different tools for different jobs.

It doesn't have to sound identical.. two different branded tube amps won't sound identical either.
If it sounds good and has the authority in tone you like - that's all you need. I traded in an svt in the eighties because I liked the sound of an all SS mosfet trace elliot. Yeah they sounded different. That's was the point. If they sounded the same...
Now I have a wonderful class D Genzler Magellan 800. It has all the authority of my previous amps and weighs next to nothing. Sound is incredible especially paired with a new neo cab ( another genzler product a BA12-3)
This is the best sounding and lightest rig I've ever owned - sorry to all the TE and SVT fanboys...

Absolutely correct. Choose something that works for you and makes you happy. If all bass amps sounded the same, or if all basses sounded the same, wouldn't the world be boring???

It’s funny because so many years ago when micros were first coming out you had a demographic of people that swore up and down that these new amps had no drawback, sounded just as good at any volume as lead sleds did, and would stop just short of questioning your intelligence if your opinion differed.

Now that there’s a new generation of micros, these same people are saying they can’t believe how much these new amps have improved upon the prior models in sound and feel

I think every adult could benefit from taking an entry level psychology course.

Or some folks could learn from the evolution of products?

What I think you have missed is that products evolve, design philosophies evolve, tastes evolve, and needs evolve.

I've been doing this long enough that I can look back over quite a few generations of products that I have designed, as well as products that I competed against. Without any doubt, all of us as designers have evolved and made different choices in preamp and power amp design based on tastes, player feedback and availability of parts and technology.

I can also look back and easily compare my lead sled designs with class D designs, and both types have evolved. My last lead sled design was different from my first, not just the power amp but also the preamp. When developing our first SMPS based design (a transition product), I built up a conventional toroidal transformer and SMPS power supply, each driving an identical power amp (class AB), and adjusted the SMPS to so closely mimic the toroidal supply that nobody could tell in a blind listening or playing test. Which is "better"? Who knows and frankly who cares because nobody could tell the difference. The choice was made to go with the SMPS and that's how the NeoPak 3.5 came about.